This is a Mentored Research Scientist Development Award (K01) application to support the PI's establishment of an independent line of research examining the causal mechanisms of addictive behavior in general and smoking in particular. The training goals, which will be met through an active mentored research plan as well as formal coursework, seminars, directed readings, and workshops, are: (1) to develop an expertise in the use of Ecological Momentary Assessment (EMA) methodology, (2) to develop an expertise in health behavior theories (HBT) and their application to smoking cessation, (3) to acquire specialized training for the analysis of EMA data, and (4) to increase scholarly productivity. The purpose of the proposed research project is to examine the role of smoking outcome expectancies (OEs) in college student smoking cessation. The proposed study utilizes an intensive longitudinal quasi-experimental design using EMA methodology to capture changes in smoking outcome expectancies in college student smokers undergoing a quit attempt. The goal is to delineate the temporal ordering of changes in smoking OEs and smoking cessation. Correlational and cross-sectional support exists that demonstrates that negative OEs outweigh positive OEs in former smokers compared to current smokers. Missing from current evidence is a temporally specific delineation of when in the process of smoking cessation changes in OEs occur, and whether changes in OEs lead to behavior change, as HBTs postulate, or behavior change leads to changes in OEs, as Cognitive Dissonance Theory (Festinger, 1957) postulates. Participants (n=120) will self-monitor smoking behaviors and attitudes during 4 weeks: baseline (1 week), during which processes are naturalistically recorded, pre-quit (1 week), beginning after the onset of treatment, and post-quit (2 weeks), beginning on the quit day; long-term follow-up will be assessed 3-months later. To facilitate smoking cessation, participants will partake in treatment (three brief advice sessions, nicotine replacement therapy). Reports are made several times a day through the use of palm-top computers, using both event-based and time-based sampling approaches. Taken together, this K01 award would allow the PI to build upon her existing strengths of advanced statistical training and experience with theory-driven health behavior interventions to enable her to take full advantage of modern technology to delineate the causal mechanisms underlying the process of smoking cessation.